[Prajapati, 3(3): March, 2014] IN: 2277-9655 IJERT INTERNATIONAL JOURNAL OF ENGINEERING CIENCE & REEARCH TECHNOLOGY Low Power and Low Dead Zone Phase Frequency Detector in PLL Jaimini Prajapati *1, Kiran Patel 2, Kruti Thakor 3, Nilesh Patel 4 *1,2 PG tudent, Electronics and Communication, GTU, LCIT- Bhandu, Mehsana, India 3 Assitant professor, Electronics & Communication, LDRP-ITR, Gandhinagar, India 4 Research cholar, Institute of Technology, Nirma University, Ahmedabad, Gujarat, India Jaimini104@gmail.com Abstract This article presents Low power and Low Dead Zone Phase Frequency Detector for phase locked loop feedback system. It describes a design of a Phase Frequency Detector () using AND Gate and NOR Gate for 50 M and frequency and also the comparative analysis of power dissipation and Dead Zone for 50M and frequency. The Phase Frequency Detector is operated at 1.8V power supply. The proposed architecture of has been implemented using 0.18µm CMO Technology in ELDO- Mentor Graphics tool. Keywords: Mentor Graphics; CMO; DPLL; Introduction Low jitter and Low power phase lock loop is becoming essential for portable and battery operated compact electronic devices, which decreases the risk of reliability problems. o power and jitter have been major concern in circuit designs from last decade. Now a day, the design of low power and low jitter PLL for the different application has become one of the greatest challenges task in highperformance very large scale integration (VLI) design. As a consequence, many techniques have been introduced to minimize the power and reduction in jitter of new VLI circuits. A Phase Locked Loop also multiplies a low frequency reference clock signal, to produce a high frequency output clock signal. A PLL is a negative feedback control system. As the name implies, the main purpose of the PLL is to generate a signal in which the phase is the same as the phase of a reference clock signal. This is done after many iteration of comparing the reference and feedback signal. The overall goal of the PLL is to match the reference and feedback signal in phase, this is the lock mode. After this, the PLL continues to compare the two signals but since they are in lock mode, the PLL output is constant. A basic form of a PLL that consists of five main blocks: 1. Phase Frequency Detector () 2. Charge Pump (CP) 3. Low Pass Filter (LPF) 4. Voltage Controlled Oscillator (VCO) 5. Divide by N Network The basic block diagram of the Phase Locked Loop feedback system is shown in figure 1. Figure 1: A Basic Block Diagram of Phase Locked Loop As shown in figure 1, the phase frequency detector produce an error signal based on the phase differences between the phase of two input signal that is reference signal data in and the feedback clock signal dclock. If there is a phase difference between the two signals, it generates an error signal. This error signal drives the low pass filter, which increases or decreases the control voltage. This controlled voltage is the input of the Voltage Controlled Oscillator (VCO). Thus, the LPF is necessary to only allow DC signals into the VCO and is also necessary to store the charge. The purpose of the VCO is to speed up or slow down the feedback signal according to the error generated by the. The average difference in time between the phases of the two Input reference and feedback http: // www.ijesrt.com(c)international Journal of Engineering ciences & Research Technology
[Prajapati, 3(3): March, 2014] IN: 2277-9655 signals when the PLL has achieved lock is called the static phase offset (steady-state phase error) and this variance is called jitter. Power is a limiting factor in VLI integration for portable applications. The resulting heat dissipation also limits the feasible packaging and performance of the VLI chip [5]. ince the dynamic power dissipation in synchronous digital integrated circuit is determined by CV2f, reducing the supply voltage is an effective way to reduce power [4]. The paper is organized as follows. ection II contains design issues of phase frequency detector circuit and characterization. ection III contains of two phase frequency detector in two different technologies with detailed circuit diagram and simulated output. ection IV contains the table of specifications with results. ection V concludes the best for low Dead Zone and low power PLL. frequency detector is also known as the sequential detector. Phase Frequency detector () is a digital circuit detecting phase or frequency difference between reference clock and output of voltage controlled oscillator (VCO) clock signal and generates output signal if frequency of VCO is to be increased or decreased. drives the Charge Pump (CP) and adjust the amount of the current to be injected to or from the loop filter capacitor. If there is a phase difference between the two input signals, it generates up or down synchronized signals to the charge pump. Design Issues Dead zone is due to small phase error, when both the input signals of are very close to each other but two output signals are not able to generate this error it will create the problem that is nothing but dead zone. Fig.2 Dead Zone Fig. 2 shows the lock condition of the with dead zone. Dead zone is due to the delay time of the internal logic components of digital circuit and the reset time that requires by the reset path to reset the flip flop of the. Due to this dead zone problem the output jitter will create and the sensitivity of the is affected by this. In this case the sensitivity means the smallest phase difference the can detect and produce at the output UP or DOWN signal. This lead to the conclusion that the higher the sensitivity the better the. Circuit Architecture of Phase Frequency Detector A. using AND Gate A schematic diagram of the phase frequency detector using AND Gate is shown in the figure 3. The output of the depends on both the phase and frequency of the inputs. This type of the phase Figure 3: A Basic Block Diagram of Phase Frequency Detector The operation of this circuit is based on two D-type flip- flop and simple AND gate in the reset path. Each flip-flop has the D-input wired logic high. Under this condition, the flip-flop with a low Q output will transition to high on the next rising edge of its clock input. Also if such a transition occurs when Q is high, then there will no change in the flipflop state. A high signal on a reset input will force Q low as soon as the reset signal is applied. Finally, logic high on both of the Q output causes the resetting of both the flip-flo. The generates two output signals that are not complementary to each other. The output signal depends not only on the phase error, but also on the frequency error. If the frequency, ω A, of the input signal A is less than that of input signal B, ω B, then the produces positive pulses at Q A, while Q B remains zero. ame as, if ω A > ω B, then positive pulses appear at Q B while Q A remain zero. If ω A = ω B, then circuit generates pulses at either Q A or Q B with a width equal to the phase difference between the two inputs. so the average value of the Q A - Q B is proportional to the frequency or the phase difference between the inputs at data and dclock. The outputs Q A and Q B are called the up and down signals. The UP pulse is the difference between the phases of the two clock input signals. This UP pulse indicates that the feedback signal needs to speed up with the reference signal. In the second http: // www.ijesrt.com(c)international Journal of Engineering ciences & Research Technology
[Prajapati, 3(3): March, 2014] IN: 2277-9655 case, when the feedback signal is leading the reference clock signal, the DOWN pulse represents the difference between the phases of the two clock input signals. The implementation of the using AND Gate in the reset path with CMO 0.18µm technology is as shown in the figure 4..The simulated output of this is shown in figure 5. imulation is done with the ELDO-MENTOR GRAPHIC TOOL Figure 7: at 50M (Dclock Leads Data) Figure 5 shows, the lock condition of the, both the output signals up and dn signals are low. Figure 6 and 7 the data leading condition and the dclock leading condition, the pulse width of the up signal or dn signal shows the relative value of the error generated between two inputs of the. This error value is applied to the charge pump. Figure 4: Implementation of Phase Frequency Detector Figure 8: Dead Zone of the (50M) Figure 5: at 50M (Lock Condition) B. using NOR Gate In Fig.9 shows the using NOR gate in reset path. The circuit consists of two resettable, edge triggered D flip flo with their D inputs tied to logic 1 and a NOR Gate in the reset path [3]. The data and dclock serve as clocks signal of the flip flo. The up and dn signals are given as input to the NOR gate in the reset path. When the rising edge of data leads that of dclock, then up goes to logic low i.e. UP kee high until the rising edge of dclock makes dn on low level. Because up and dn are NORed, so REET goes to logic high and resets the into the initial state Figure 6: at 50M (Data Leads Dclock) http: // www.ijesrt.com(c)international Journal of Engineering ciences & Research Technology
[Prajapati, 3(3): March, 2014] IN: 2277-9655 Fig.9 NOR Gate based The implementation of the using NOR Gate in the reset path with CMO 0.18µm technology is as shown in the figure 10.The simulated output of this is shown in figure 11. imulation is done with the ELDO-MENTOR GRAPHIC TOOL Figure 12: at 50M (Data Leads Dclock) Figure:10 implementation of NOR Gate Figure 13: at 50M (Data Leads Dclock) Figure 10 shows, the lock condition of the NOR Gate, both the output signals UP and DWN signals are low. Figure 11 and 12 the data leading condition and the dclock leading condition, the pulse width of the UP signal or DN signal shows the relative value of the error generated between two inputs of the. This error value is applied to the charge pump. Figure 14: Dead Zone of the NOR Gate (50M) Figure 11: at 50M (Lock Condition) As shown in figure 13, the Dead Zone of NOR Gate is 125 At 50 M Frequency http: // www.ijesrt.com(c)international Journal of Engineering ciences & Research Technology
[Prajapati, 3(3): March, 2014] IN: 2277-9655 imulation Result NOR AND NOR AND Parameter Technolog 0.18µ 0.18µ y m m 0.9µm 0.9µm Input Frequency 50M 50M 50M 50M Transistor count 20 22 20 22 Power Consumpti on 3.0715 3.7672 3.0588 3.4746 Dead zone 300 321 125 192 Glitch Period 375 468.75 182.22 200 Table 1: Comparison of Jitter and Power Dissipation of at 50M frequency Parameter Technolog y Input Frequency Transistor count Power Consumpti on Dead zone Glitch Period NOR 0.18µ m AND 0.18µ m NOR 0.9µm 20 22 20 22 4.8162 273.23 281 5.2995 292.95 359.15 4.2117 78 85.71p s AND 0.9µm 4.5209 87 94.42p s References [1] Behzad Razavi, Design of Analog CMO Integrated Circuit, New York, McGrow- Hill, 2002, Ch. 5, pp. 135-165. [2] Raj Nandini, Himadri ingh Raghav, B.P.ingh Comparison of Phase Frequency Detectors by Different Logic Gates International Journal of Innovative Technology and Exploring Engineering (IJITEE) IN: 2278-3075, Volume-2, Issue- 5, April 2013 [3] Vaijayanti Lule1, M.A. Gaikwad2, V.G.Nasre3 : Low Power 0.18um CMO Phase Frequency Detector International Journal of Emerging Technology and Advanced Engineering (IJETAE) (IN 2250-2459, Volume 2, Issue 7, July 2012). [4] Kruti P. Thakore, Harikrishna C. Parmar : High peed with Charge Pump and Loop Filter for Low Jitter and Low Power PLL International Journal of Emerging Technology and Advanced Engineering (IJETAE) IN : 2230-7109 Vol. 2, Issue 2, June 2011 [5] Kashyap K. Patel1, Nilesh D. Patel: Phase Frequency Detector and Charge Pump For DPLL Using 0.18µm CMO Technology International Journal of Emerging Technology and Advanced Engineering (IJETAE) (IN 2250-2459, IO 9001:2008 Certified Journal, Volume 3, Issue1,January 2013). Table 2: Comparison of Jitter and Power Dissipation of at frequency Conclusion A Phase Frequency Detector with NOR Gate and AND Gate in the reset path is designed with 0.18µm CMO technology, 1.8v power supply, 50 M and input frequency. The Dead Zone of the AND Gate and NOR Gate design is 87 and 78 at frequency. The total power dissipation of the AND Gate and NOR Gate circuit is 0.42mwatt and 0.45mwatt.so NOR Gate Is best for PLL because it has low Dead Zone and low power consumption. This paper has represented comparative analysis of different frequencies for jitter and power dissipation. http: // www.ijesrt.com(c)international Journal of Engineering ciences & Research Technology